﻿#define BOOST_ASIO_HAS_CO_AWAIT

#include <boost/beast/core.hpp>
#include <boost/beast/http.hpp>
#include <boost/beast/version.hpp>
#include <boost/asio/ip/tcp.hpp>
#include <boost/asio/awaitable.hpp>
#include <boost/asio/co_spawn.hpp>
#include <boost/asio/use_awaitable.hpp>
#include <boost/config.hpp>
#include <algorithm>
#include <cstdlib>
#include <iostream>
#include <memory>
#include <string>
#include <thread>
#include <vector>

#include "gtest/gtest.h"
#include "log.h"

namespace beast = boost::beast;         // from <boost/beast.hpp>
namespace http = beast::http;           // from <boost/beast/http.hpp>
namespace net = boost::asio;            // from <boost/asio.hpp>
using tcp = boost::asio::ip::tcp;       // from <boost/asio/ip/tcp.hpp>


using tcp_stream = typename beast::tcp_stream::rebind_executor<
        net::use_awaitable_t<>::executor_with_default<net::any_io_executor>>::other;

// Return a reasonable mime type based on the extension of a file.
beast::string_view
mime_type(beast::string_view path) {
    using beast::iequals;
    auto const ext = [&path] {
        auto const pos = path.rfind(".");
        if (pos == beast::string_view::npos)
            return beast::string_view{};
        return path.substr(pos);
    }();
    if (iequals(ext, ".htm")) return "text/html";
    if (iequals(ext, ".html")) return "text/html";
    if (iequals(ext, ".php")) return "text/html";
    if (iequals(ext, ".css")) return "text/css";
    if (iequals(ext, ".txt")) return "text/plain";
    if (iequals(ext, ".js")) return "application/javascript";
    if (iequals(ext, ".json")) return "application/json";
    if (iequals(ext, ".xml")) return "application/xml";
    if (iequals(ext, ".swf")) return "application/x-shockwave-flash";
    if (iequals(ext, ".flv")) return "video/x-flv";
    if (iequals(ext, ".png")) return "image/png";
    if (iequals(ext, ".jpe")) return "image/jpeg";
    if (iequals(ext, ".jpeg")) return "image/jpeg";
    if (iequals(ext, ".jpg")) return "image/jpeg";
    if (iequals(ext, ".gif")) return "image/gif";
    if (iequals(ext, ".bmp")) return "image/bmp";
    if (iequals(ext, ".ico")) return "image/vnd.microsoft.icon";
    if (iequals(ext, ".tiff")) return "image/tiff";
    if (iequals(ext, ".tif")) return "image/tiff";
    if (iequals(ext, ".svg")) return "image/svg+xml";
    if (iequals(ext, ".svgz")) return "image/svg+xml";
    return "application/text";
}

// 将 HTTP 相对路径附加到本地文件系统路径
// 返回的路径针对平台进行了规范化
// Append an HTTP rel-path to a local filesystem path.
// The returned path is normalized for the platform.
std::string
path_cat(
        beast::string_view base,
        beast::string_view path) {
    if (base.empty())
        return std::string(path);
    std::string result(base);
#ifdef BOOST_MSVC
    char constexpr path_separator = '\\';
    if (result.back() == path_separator)
        result.resize(result.size() - 1);
    result.append(path.data(), path.size());
    for (auto &c: result)
        if (c == '/')
            c = path_separator;
#else
    char constexpr path_separator = '/';
    if (result.back() == path_separator)
        result.resize(result.size() - 1);
    result.append(path.data(), path.size());
#endif
    return result;
}

#ifdef boost_182
// Return a response for the given request.
//
// The concrete type of the response message (which depends on the
// request), is type-erased in message_generator.
template<class Body, class Allocator>
http::message_generator
handle_request(
        beast::string_view doc_root,
        http::request<Body, http::basic_fields<Allocator>> &&req) {
    // Returns a bad request response
    auto const bad_request = [&req](beast::string_view why) {
        http::response<http::string_body> res{http::status::bad_request, req.version()};
        res.set(http::field::server, BOOST_BEAST_VERSION_STRING);
        res.set(http::field::content_type, "text/html");
        res.keep_alive(req.keep_alive());
        res.body() = std::string(why);
        res.prepare_payload();
        return res;
    };

    // Returns a not found response
    auto const not_found = [&req](beast::string_view target) {
        http::response<http::string_body> res{http::status::not_found, req.version()};
        res.set(http::field::server, BOOST_BEAST_VERSION_STRING);
        res.set(http::field::content_type, "text/html");
        res.keep_alive(req.keep_alive());
        res.body() = "The resource '" + std::string(target) + "' was not found.";
        res.prepare_payload();
        return res;
    };

    // Returns a server error response
    auto const server_error = [&req](beast::string_view what) {
        http::response<http::string_body> res{http::status::internal_server_error, req.version()};
        res.set(http::field::server, BOOST_BEAST_VERSION_STRING);
        res.set(http::field::content_type, "text/html");
        res.keep_alive(req.keep_alive());
        res.body() = "An error occurred: '" + std::string(what) + "'";
        res.prepare_payload();
        return res;
    };

    auto const server_ok = [&req]() {
        // Respond to GET request
        http::response<http::string_body> res{http::status::ok, req.version()};
        res.set(http::field::server, BOOST_BEAST_VERSION_STRING);
        res.set(http::field::content_type, "text/html");
        res.body() = R"({"code': 200})";
        res.prepare_payload();
        res.keep_alive(req.keep_alive());
        return res;
    };

    return server_ok();

    // Make sure we can handle the method
    if (req.method() != http::verb::get &&
        req.method() != http::verb::head)
        return bad_request("Unknown HTTP-method");

    // Request path must be absolute and not contain "..".
    if (req.target().empty() ||
        req.target()[0] != '/' ||
        req.target().find("..") != beast::string_view::npos)
        return bad_request("Illegal request-target");

    // Build the path to the requested file
    std::string path = path_cat(doc_root, req.target());
    if (req.target().back() == '/')
        path.append("index.html");

    // Attempt to open the file
    beast::error_code ec;
    http::file_body::value_type body;
    body.open(path.c_str(), beast::file_mode::scan, ec);

    // Handle the case where the file doesn't exist
    if (ec == beast::errc::no_such_file_or_directory)
        return not_found(req.target());

    // Handle an unknown error
    if (ec)
        return server_error(ec.message());

    // Cache the size since we need it after the move
    auto const size = body.size();

    // Respond to HEAD request
    if (req.method() == http::verb::head) {
        http::response<http::empty_body> res{http::status::ok, req.version()};
        res.set(http::field::server, BOOST_BEAST_VERSION_STRING);
        res.set(http::field::content_type, mime_type(path));
        res.content_length(size);
        res.keep_alive(req.keep_alive());
        return res;
    }

    // Respond to GET request
    http::response<http::file_body> res{
            std::piecewise_construct,
            std::make_tuple(std::move(body)),
            std::make_tuple(http::status::ok, req.version())};
    res.set(http::field::server, BOOST_BEAST_VERSION_STRING);
    res.set(http::field::content_type, mime_type(path));
    res.content_length(size);
    res.keep_alive(req.keep_alive());
    return res;
}

//------------------------------------------------------------------------------


// Handles an HTTP server connection
net::awaitable<void>
do_session(
        tcp_stream stream,
        std::shared_ptr<std::string const> doc_root) {
    // This buffer is required to persist across reads
    beast::flat_buffer buffer;

    // This lambda is used to send messages
    try {
        for (;;) {
            // Set the timeout.
            stream.expires_after(std::chrono::seconds(30));

            // Read a request
            http::request<http::string_body> req;
            co_await http::async_read(stream, buffer, req);

            // Handle the request
            http::message_generator msg =
                    handle_request(*doc_root, std::move(req));

            // Determine if we should close the connection
            bool keep_alive = msg.keep_alive();

            // Send the response
            co_await beast::async_write(stream, std::move(msg), net::use_awaitable);

            if (!keep_alive) {
                // This means we should close the connection, usually because
                // the response indicated the "Connection: close" semantic.
                break;
            }
        }
    }
    catch (boost::system::system_error &se) {
        if (se.code() != http::error::end_of_stream)
            throw;
    }

    // Send a TCP shutdown
    beast::error_code ec;
    stream.socket().shutdown(tcp::socket::shutdown_send, ec);

    // At this point the connection is closed gracefully
    // we ignore the error because the client might have
    // dropped the connection already.
}

//------------------------------------------------------------------------------

// Accepts incoming connections and launches the sessions
net::awaitable<void>
do_listen(
        tcp::endpoint endpoint,
        std::shared_ptr<std::string const> doc_root) {
    // Open the acceptor
    auto acceptor = net::use_awaitable.as_default_on(tcp::acceptor(co_await net::this_coro::executor));
    acceptor.open(endpoint.protocol());

    // Allow address reuse
    acceptor.set_option(net::socket_base::reuse_address(true));

    // Bind to the server address
    acceptor.bind(endpoint);

    // Start listening for connections
    acceptor.listen(net::socket_base::max_listen_connections);

    for (;;)
        boost::asio::co_spawn(
                acceptor.get_executor(),
                do_session(tcp_stream(co_await acceptor.async_accept()), doc_root),
                [](const std::exception_ptr &e) {
                    if (e)
                        try {
                            std::rethrow_exception(e);
                        }
                        catch (std::exception &e) {
                            LOG_ERROR << "Error in session: " << e.what();
                        }
                });

}
#endif

#include <boost/asio.hpp>
#include <type_traits>

using namespace boost;

asio::awaitable<void> http_request(asio::ip::tcp::socket socket, const asio::ip::tcp::endpoint &endpoint) {
    char read_buf[4096]{};

    try {
        // Asio的设计很灵活，`asio::use_awaitable`这个参数可以通过一些手段忽略掉。
        co_await socket.async_connect(endpoint, asio::use_awaitable);
        co_await socket.async_send(asio::buffer("GET / HTTP/1.0\r\n\r\n"), asio::use_awaitable);
        co_await socket.async_receive(asio::buffer(read_buf), asio::use_awaitable);

        LOG_INFO << read_buf;
    } catch (const std::exception &e) {
        LOG_INFO << endpoint << " " << e.what();
    }
}

TEST(coroutines_asio, http_client) {
    asio::io_context ctx;
    asio::ip::tcp::endpoint endpoint{asio::ip::make_address("127.0.0.1"), 80};
    asio::ip::tcp::socket socket{ctx};

    asio::co_spawn(ctx, http_request(std::move(socket), endpoint), asio::detached);

    ctx.run();
}

#ifdef boost_182
TEST(coroutines_asio, cat_test) {

    auto const address = net::ip::make_address("127.0.0.1");
    auto const port = static_cast<unsigned short>(81);
    auto const doc_root = std::make_shared<std::string>("/");
    auto const threads = std::max<int>(1, 1);

    // The io_context is required for all I/O
    net::io_context ioc{threads};

    // 使用boost::asio::spawn()开启一个协程
    // Spawn a listening port
    boost::asio::co_spawn(ioc,
                          do_listen(tcp::endpoint{address, port}, doc_root),
                          [](const std::exception_ptr &e) {
                              if (e)
                                  try {
                                      std::rethrow_exception(e);
                                  }
                                  catch (std::exception &e) {
                                      std::cerr << "Error in acceptor: " << e.what() << "\n";
                                  }
                          });

    // Run the I/O service on the requested number of threads
    std::vector<std::thread> v;
    v.reserve(threads - 1);
    for (auto i = threads - 1; i > 0; --i)
        v.emplace_back(
                [&ioc] {
                    ioc.run();
                });
    ioc.run();


}


#include "boost/pfr.hpp"

class my_struct_c { // no ostream operator defined!
public:
    int i;
    char c;
    double d;
private:
    int b;

public:
    my_struct_c(int i, char c, double d, int b) : i(i), c(c), d(d), b(b) {}
};

TEST(HTTP, printf_struct) {

    struct my_struct { // no ostream operator defined!
        int i;
        char c;
        double d;
    };

    my_struct s{100, 'H', 3.141593};
    std::cout << "my_struct has " << boost::pfr::tuple_size<my_struct>::value
              << " fields: " << boost::pfr::io(s) << "\n";

}
#endif